1. Field of the Invention
The present invention relates to a magnetic head slider manufacturing method and, more specifically, to a method for manufacturing a magnetic head slider that has a magnetic head formed with thin films.
2. Description of the Related Art
Recent advancement in the recording density of magnetic disk devices has been remarkable, and it has continued to grow. So far, mainly employed is a recording method called a longitudinal recording method which places magnetic data horizontally with respect to a disk surface. With the longitudinal recording method, however, magnetic poles repel each other. Thus, it is difficult to have higher density. Even if it becomes possible to achieve higher density by suppressing repelling of the magnetic poles through thinning films of a recording medium, it is unavoidable to have an issue of heat disturbance with which the recording magnetization becomes unstable because of the heat energy of a room temperature. Therefore, recently, there has been achieved a perpendicular-recording type magnetic disk device with which the recording density can be improved further.
The perpendicular-recording method has such a characteristic that a diamagnetic field working between neighboring bits becomes reduced as the linear recording density is increased, and that the recording magnetism can be stably maintained. Thus, the higher the density becomes, the more the recording magnetism is stabilized. Therefore, it is effective as a technique for achieving super high-density recording. Specifically, the perpendicular recording method is a magnetic recording method which records information by applying a magnetic field to a recording layer sandwiched between a backing soft magnetic layer of a double-layered recording medium and a magnetic monopole head so as to magnetize the magnetic substance of the recording layer towards a direction perpendicular to the disk surface. With the perpendicular recording method, it is necessary to shorten the height (neck height) of the main magnetic pole of the perpendicular magnetic recording head as much as possible in order to obtain a large recording magnetic field. However, if the height is too short, fringing fields are generated. In the meantime, when it is too long, recording may be erased because of residual magnetism. That is, it is necessary to fabricate the recording head with high precision, since the height of the recording element affects greatly on the recording property.    Patent Document 1: Japanese Unexamined Patent Publication 2006-172691    Patent Document 2: Japanese Unexamined Patent Publication 2006-331562
However, with the conventional longitudinal recording method, accuracy in the height of the magnetic pole of the recording element has not been sought so severely. In the meantime, high precision is sought for the height of a reproducing element even with the longitudinal recording method. This is the same for the perpendicular recording method. Therefore, it is desired to fabricate both the reproducing element and the recording element with high precision for the perpendicular recording method.
Patent Document 1 discloses a method which polishes both the reproducing element and the recording element by adjusting angle of a jig by a laser auto collimator or the like. However, this method has such an issue that both elements cannot be adjusted with high precision since variations in the recording element cannot be suppressed even by adjusting the angle of an element forming face of a head with respect to a flying surface, if positions of the reproducing element and the recording element which are already being stacked on a wafer are shifted.
Patent Document 2 discloses a method which measures the heights of the reproducing element and the recording element after polishing, and adjusts the angle of polishing surface of a next bar. However, this method cannot adjust the angle during the actual polishing, so that it is not possible to set the elements in all the magnetic heads with high precision.
Further, the method disclosed in Patent Document 2 uses a polish amount detecting sensor for detecting the heights of the elements when lapping the reproducing element and the recording element. However, the height of each element is proportional to a reciprocal of the resistance of the polish amount detecting sensor. Thus, the resistance changing rate of the sensor is small in an area where the height is long, so that it is hard to see the shift between the recording element and the reproducing element. When the resistance changing rate becomes actually large, the height has already become very short. Thus, when the angle is to be adjusted at that point, it cannot be adjusted sufficiently. As a result, there comes to have two surfaces to be polished.